Use 4000 as the local dev port instead

Matches Jekyll etc

README.md

@@ -15,7 +15,7 @@ Then run `skiff dev` to start the development server.
 ...otherwise, you can run a dockerized version via an alias (add this to your .bashrc or similar to simplify re-use). On macOS, use:
 
 ```sh
-alias skiff-dev="docker build -t skiff-site . && docker run -it --rm -p 8080:80 -v ./public:/site/public --name skiff-site skiff-site nginx '-g daemon off;'"
+alias skiff-dev="docker build -t skiff-site . && docker run -it --rm -p 4000:80 -v ./public:/site/public --name skiff-site skiff-site nginx '-g daemon off;'"
 alias skiff="docker run -it --rm -v '${PWD}:/workdir' -v /run/host-services/ssh-auth.sock:/run/host-services/ssh-auth.sock -e SSH_AUTH_SOCK='/run/host-services/ssh-auth.sock' -v /var/run/docker.sock:/var/run/docker.sock ghcr.io/basecamp/kamal-skiff:latest"
 ```
 

lib/skiff/cli.rb

@@ -20,10 +20,10 @@ def new(site_name)
  desc "dev", "Start development server"
  def dev
  if File.exist?("Dockerfile")
- puts "Starting #{site_name} on http://localhost:8080..."
+ puts "Starting #{site_name} on http://localhost:4000..."
 
  docker "build -t #{site_name} ."
- docker "run -it --rm -p 8080:80 -v ./public:/site/public --name #{site_name} #{site_name} nginx '-g daemon off;'"
+ docker "run -it --rm -p 4000:80 -v ./public:/site/public --name #{site_name} #{site_name} nginx '-g daemon off;'"
  else
  say "No Dockerfile found in current directory", :red
  end